如何在Swift中检测并应用横向方向到AVCaptureVideoPreviewLayer？

Question

我基本上是在回答这个问题AVCaptureVideoPreviewLayer orientation - need landscape，除了在Swift。

我的目标是iOS 8，而AVCaptureVideoPreviewLayer似乎没有setVideoOrientation功能。

我应该如何检测方向已更改，并正确旋转AVCaptureVideoPreviewLayer？

Answer 1

检测并应用于viewWillLayoutSubviews。

这是如何做：

override func viewWillLayoutSubviews() {

    let orientation: UIDeviceOrientation = UIDevice.currentDevice().orientation
    print(orientation)

    switch (orientation) {
    case .Portrait:
        previewLayer?.connection.videoOrientation = .Portrait
    case .LandscapeRight:
        previewLayer?.connection.videoOrientation = .LandscapeLeft
    case .LandscapeLeft:
        previewLayer?.connection.videoOrientation = .LandscapeRight
    default:
        previewLayer?.connection.videoOrientation = .Portrait
    }
}

Answer 2

更新Swift 3

  override func viewWillLayoutSubviews() {

    let orientation: UIDeviceOrientation = UIDevice.current.orientation
    print(orientation)

    switch (orientation) {
    case .portrait:
        videoPreviewLayer?.connection.videoOrientation = .portrait
    case .landscapeRight:
        videoPreviewLayer?.connection.videoOrientation = .landscapeLeft
    case .landscapeLeft:
        videoPreviewLayer?.connection.videoOrientation = .landscapeRight
    case .portraitUpsideDown:
            videoPreviewLayer?.connection.videoOrientation = .portraitUpsideDown
    default:
        videoPreviewLayer?.connection.videoOrientation = .portraitUpsideDown
    }
}

Answer 3

对我来说，当我向左或向右旋转iPad时，我需要它来改变方向，帮助我的解决方案是：

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    let orientation = UIDevice.current.orientation

    switch (orientation) {
    case .portrait:
        videoPreviewLayer?.connection.videoOrientation = .portrait
    case .landscapeLeft:
        videoPreviewLayer?.connection.videoOrientation = .landscapeRight
    case .landscapeRight:
        videoPreviewLayer?.connection.videoOrientation = .landscapeLeft
    default:
        videoPreviewLayer?.connection.videoOrientation = .portrait
    }
}

Answer 4

ViewController中的Xamarin解决方案;

public override void ViewWillLayoutSubviews()
    {
        base.ViewWillLayoutSubviews();

        var videoPreviewLayerConnection = PreviewView.VideoPreviewLayer.Connection;
        if (videoPreviewLayerConnection != null)
        {
            var deviceOrientation = UIDevice.CurrentDevice.Orientation;
            if (!deviceOrientation.IsPortrait() && !deviceOrientation.IsLandscape())
                return;

            var newVideoOrientation = VideoOrientationFor(deviceOrientation);
            var oldSize = View.Frame.Size;
            var oldVideoOrientation = videoPreviewLayerConnection.VideoOrientation;
            videoPreviewLayerConnection.VideoOrientation = newVideoOrientation;
        }
    }

Answer 5

Swift 4中的另一个解决方案是使用Notification。

        NotificationCenter.default.addObserver(self,
                                           selector: #selector(detected),
                                           name: 

UIDevice.orientationDidChangeNotification，object：nil）

在选择器功能中，您可以检查方向：

let orientation: UIDeviceOrientation = UIDevice.current.orientation
switch orientation {
    case .portrait:
         stuff()
    case .landscapeLeft:
         stuffOther()
    case .landscapeRight
         stuffOther()
    default:
         stuffOther()
}

请记住在没有必要时删除观察者。

非常重要：你的物理iPhone必须没有锁定旋转（我已经失去了2小时，因为在这种情况下，方法不会被截获:)）。